OVMS3-idf/components/esp32/include/xtensa/overlay.h

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2016-08-17 15:08:22 +00:00
// overlay.h -- Overlay manager header file
// $Id$
// Copyright (c) 2013 Tensilica Inc.
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be included
// in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
// IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
// TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
// SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#ifndef OVERLAY_H
#define OVERLAY_H
#include <xtensa/xtruntime.h>
#ifdef __cplusplus
extern "C" {
#endif
// Define this to turn off overlay support
#ifdef XT_DISABLE_OVERLAYS
#define OVERLAY(n)
#define DECLARE_OVERLAY(n)
#define xt_overlay_map(ov_id)
#define xt_overlay_map_async(ov_id) 0
#define xt_overlay_map_in_progress() 0
#define xt_overlay_get_id() 0
#define xt_overlay_get_state(pc) 0
#define xt_overlay_check_map(pc,ps,ovstate,sp) 0
#else
// Shorthand for convenience and portability.
#define OVERLAY(n) __attribute__((overlay(n)))
// Structure of the overlay table required by gdb and the overlay
// manager. Should not be accessed by user code unless overriding
// the load process.
struct ovly_table {
void * vma; // The overlay's mapped address.
unsigned int size; // The size of the overlay, in bytes.
void * lma; // The overlay's load address.
unsigned int mapped; // Non-zero if overlay is currently mapped; zero otherwise.
};
// Constructed by the linker. Required for gdb and for the overlay
// manager. Should not be accessed by user code unless overriding
// the load process.
extern struct ovly_table _ovly_table[];
// Functions.
void xt_overlay_map(int ov_id);
int xt_overlay_map_async(int ov_id);
int xt_overlay_map_in_progress(void);
unsigned int xt_overlay_get_state(unsigned int pc);
unsigned int xt_overlay_check_map(unsigned int * pc, unsigned int * ps,
unsigned int ovstate, unsigned int sp);
int xt_overlay_start_map(void * dst, void * src, unsigned int len, int ov_id);
int xt_overlay_is_mapping(int ov_id);
void xt_overlay_fatal_error(int ov_id);
// Returns the current overlay ID. If no overlay is mapped or an overlay
// is in the middle of being mapped, returns -1. Inlined to avoid calling
// out of overlay (wastes cycles, can end up reading wrong ID on interrupt
// activity).
//
static inline int xt_overlay_get_id(void)
{
#pragma always_inline
extern short _mapping_id;
extern short _ovly_id;
int ret;
unsigned int flags = XTOS_SET_INTLEVEL(15);
if (_mapping_id >= 0) {
ret = -1;
}
else {
ret = _ovly_id;
}
XTOS_RESTORE_INTLEVEL(flags);
return ret;
}
// The following macros are used to declare numbered overlays and generate
// the corresponding call stubs. Use as follows:
//
// DECLARE_OVERLAY(n)
//
// See documentation for more details.
//#include <xtensa/config/core-isa.h>
// At this time overlays are not supported without windowing.
#if defined(__XTENSA_WINDOWED_ABI__)
#define xstr(x) str(x)
#define str(x) #x
// At entry, register a8 holds the return address and a9 holds the target
// function address. This stub saves a8 on the stack at (SP - 20) which
// is the only location that is safe for us to use. Then it allocates 32
// bytes on the stack for working storage, loads the overlay number into
// a8, and jumps to the common handler. The common handler will make sure
// that the called function is loaded into memory before calling it.
// NOTE: we are using the stack area normally reserved for nested functions.
// This means nested functions cannot be used when overlays are in use.
#define CALL_IN(num) \
asm(".section .gnu.linkonce.t.overlay.call." xstr(num) ".text, \"ax\"\n" \
".global _overlay_call_in_" xstr(num) "_\n" \
".align 4\n" \
"_overlay_call_in_" xstr(num) "_:\n" \
"s32e a8, a1, -20\n" \
"addi a8, a1, -32\n" \
"movsp a1, a8\n" \
"movi a8, " xstr(num) "\n" \
"j _overlay_call_in_common\n" \
".size _overlay_call_in_" xstr(num) "_, . - _overlay_call_in_" xstr(num) "_\n");
// The call-out stub first calls the target function, then loads the overlay
// number into register a14 and jumps to the common handler. The handler will
// make sure that the caller function is present in memory before returning.
// Note that registers a10-a13 may contain return values so must be preserved.
//
// Because we came here via a call4, the return address is in a4, and the top
// 2 bits are set to the window increment. We'll restore the top 2 bits of
// the return address from the called function's address, assuming that both
// are in the same 1 GB segment. For now this is always true.
#define CALL_OUT(num) \
asm(".section .gnu.linkonce.t.overlay.call." xstr(num) ".text, \"ax\"\n" \
".global _overlay_call_out_" xstr(num) "_\n" \
".align 4\n" \
"_overlay_call_out_" xstr(num) "_:\n" \
"slli a4, a4, 2\n" \
"srli a4, a4, 2\n" \
"extui a8, a9, 30, 2\n" \
"slli a8, a8, 30\n" \
"or a4, a4, a8\n" \
"callx8 a9\n" \
"movi a14, " xstr(num) "\n" \
"j _overlay_call_out_common\n" \
".size _overlay_call_out_" xstr(num) "_, . - _overlay_call_out_" xstr(num) "_\n");
// Generate a call-in and a call-out stub for each overlay.
#define DECLARE_OVERLAY(num) \
CALL_IN(num) \
CALL_OUT(num)
#endif // defined(__XTENSA_WINDOWED_ABI__)
#endif // XT_DISABLE_OVERLAYS
#ifdef __cplusplus
}
#endif
#endif // OVERLAY_H